Electrical circuits mounted inside housings are used in a large variety of locations. Sometimes the circuits are used in an explosive atmosphere or where they must be protected from moisture or accidental blows. To protect them, the housings for these circuits are protectively mounted inside boxes such as condulets. Condulets are generally cylindrical in shape with a circular lid and with cable inlet and outlet tubes which communicate with the interior of the condulet for receiving electrical cables which are connected to the circuit. When the housings containing the circuits are mounted inside the condulets, they are isolated from the surrounding atmosphere, which could be explosive, humid, or corrosive, and they are protected against accidental blows.
Considerations of economy and ease of assembly make it desirable for the housing to be rapidly and releasably mounted inside the condulet without any modification of the condulet's structure.
In addition, the circuits in the housing may contain electrical components which generate considerable heat. If the housing containing the electrical circuit is itself mounted inside a condulet, heat could build up inside the housing to a level which could endanger the circuit.
Besides this, the operation of the electrical circuit inside the housing could be affected by unwanted RF signals which penetrate the housing and it is important to be able to construct the housing in such a way that this does not happen.
What is needed, therefore, and comprises an important object of this invention, is to provide a housing for an electrical circuit which can be easily and releasably mounted inside a condulet without any modification of the condulet.
Another object of this invention is to provide a housing which can be resiliently mounted inside a condulet without any modification of the condulet and without any interference with the cable inlet and cable outlet tubes in the condulet.
A further object of this invention is to provide a housing for an electrical circuit which is designed to be releasably and rigidly mounted inside a condulet and which is provided with means for preventing circuit components inside the housing from raising the temperature inside the housing to a level which could affect the performance of the circuit.
Yet a further object of this invention is to provide a housing for a circuit which has means for preventing unwanted RF signals from entering the interior of the housing.